Fuping Pan

Direct synthesis of nitrogen-doped carbon nanosheets with high surface area and excellent oxygen reduction performance.

Graphene-like nitrogen-doped carbon nanosheets (NCN) have become a fascinating carbon-based material for advanced energy storage and conversion devices, but its easy, cheap, and environmentally friendly synthesis is still a grand challenge. Herein we directly synthesized porous NCN material via the facile pyrolysis of chitosan and urea without the requirement of any catalyst or post-treatment. As-prepared material exhibits a very large BET surface area of ~1510 m(2) g(-1) and a high ratio of graphitic/pyridinic nitrogen structure (2.69 at. % graphitic N and 1.20 at. % pyridinic N). Moreover, compared to a commercial Pt/C catalyst, NCN displays excellent electrocatalytic activity, better long-term stability, and methanol tolerance ability toward the oxygen reduction reaction, indicating a promising metal-free alternative to Pt-based cathode catalysts in alkaline fuel cells. This scalable fabrication method supplies a low-cost, high-efficiency metal-free oxygen reduction electrocatalyst and also suggests an economic and sustainable route from biomass-based molecules to value-added nanocarbon materials.

A review on adsorption-enhanced photoreduction of carbon dioxide by nanocomposite materials

The large amount of CO2 emissions from the increasing consumption of fossil fuels is a potential cause for global warming. Photocatalytic reduction of CO2 using sunlight is considered as an attractive method for mitigating CO2 emissions. Extensive amount of researches on CO2 photoreduction are available, which tend to focus on the types of photocatalysts, the photocatalytic activity, and photoconversion efficiency. However, CO2 adsorption in the CO2 photoreduction process has been overlooked, despite it being an initial and important step. Recently, there has been an increase in the number of publications investigating the effects of CO2 adsorption on the CO2 photoreduction process. Thus, this review summarizes the research progress in this regard. This review focuses on the different CO2 adsorption modes and characterization methods as well as the factors influencing CO2 adsorption such as surface area, surface basicity, surface functional groups, surface defects, and exposed crystal facets. Furthermore, the design of nanocomposites that consist of photocatalysts and CO2 adsorption promoters are reviewed and discussed. It has been demonstrated that the CO2 photoreduction performance can be increased by utilizing CO2 adsorption in various types of nanocomposites, including metal oxides, chalcogenides, layered double hydroxides, and metal organic frameworks. This review provides a unique perspective in the design of nanocomposite photocatalysts with the goal of efficient CO2 photoreduction.

Self-growth-templating synthesis of 3D N,P,Co-doped mesoporous carbon frameworks for efficient bifunctional oxygen and carbon dioxide electroreduction

Although mesopore designs are expected to play a key role in exploring electrocatalytic properties of carbons, facile preparation of mesoporous carbons (MPCs) with efficient dopants to enable high performance remains a great challenge. Herein, we for the first time introduce a self-growth-templating concept for the fabrication of three-dimensional (3D) N,P,Co-doped MPC frameworks, simply through pyrolysis of vitamin B12 in NaCl assembly-enclosed nanoreactors. The route realizes the controllable formation of mesoporous templates and elimination of the templates, as well as in situ doping of N, P, and Co into MPCs in a one-step enclosed-space-assisted pyrolysis process. The highly mesoporous architecture not only enhances mass transportation but also provides the 3D electrocatalytic surface to expose highly active N,P,Co-induced dopants. These features endow MPCs with excellent activity as bifunctional electrocatalysts in oxygen reduction (E1/2 of 0.85 V, JK of 51 mA cm−2 at −0.71 V and Tafel slope of 53 mV dec−1) and CO2 reduction reactions (overpotential of −0.19 V, maximum FE of 62% for CO and Tafel slope of 129 mV dec−1), coupled with high electrochemical stability in aqueous electrolytes. We expect that the self-constructing vision can afford useful insights to guide the development of other advanced mesoporous materials other than carbon for broad applications.

Visible-Light-Driven Photocatalytic Degradation of Organic Water Pollutants Promoted by Sulfite Addition

Solar-driven heterogeneous photocatalysis has been widely studied as a promising technique for degradation of organic pollutants in wastewater. Herein, we have developed a sulfite-enhanced visible-light-driven photodegradation process using BiOBr/methyl orange (MO) as the model photocatalyst/pollutant system. We found that the degradation rate of MO was greatly enhanced by sulfite, and the enhancement increased with the concentration of sulfite. The degradation rate constant was improved by 29 times in the presence of 20 mM sulfite. Studies using hole scavengers suggest that sulfite radicals generated by the reactions of sulfite (sulfite anions or bisulfite anions) with holes or hydroxyl radicals are the active species for MO photodegradation using BiOBr under visible light. In addition to the BiOBr/MO system, the sulfite-assisted photocatalysis approach has been successfully demonstrated in BiOBr/rhodamine B (RhB), BiOBr/phenol, BiOI/MO, and Bi2O3/MO systems under visible light irradiation, as well as in TiO2/MO system under simulated sunlight irradiation. The developed method implies the potential of introducing external active species to improve photodegradation of organic pollutants and the beneficial use of air pollutants for the removal of water pollutants since sulfite is a waste from flue gas desulfurization process.

A Novel Photo-Thermo-Chemical Approach for Enhanced CO2 Reforming of Methane

We report a new approach for photo‐thermochemical CO2 (dry) reforming of methane (PTC‐DRM) to produce syngas by using concentrated sunlight as the energy input. A unique catalyst, Pt‐supported Si‐modified CeO2, was designed for this novel PTC‐DRM reaction by integrating photocatalytic and thermocatalytic effects, for which Pt was the thermocatalytic DRM catalyst and co‐catalyst for photocatalysis, CeO2 was the DRM support and semiconductor photocatalyst, and Si was the promoter and stabilizer. Under irradiation of the equivalent of 30 suns at 600 °C in 30 h, the production rates of H2 and CO reached stable levels of 90 and 154 mmol g−1 h−1, respectively, which were five and two times higher than those obtained in the dark at the same temperature. The significantly enhanced catalytic performance and stability under solar irradiation, resulting from synergy between the photocatalytic and thermocatalytic effects, demonstrates the feasibility of a new direction in low‐carbon fuel production from sunlight.

Response to Comment on “Visible-Light-Driven Photocatalytic Degradation of Organic Water Pollutants Promoted by Sulfite Addition”

9 Solar-driven heterogeneous photocatalysis has been widely studied as a promising technique for 10 degradation of organic pollutants in wastewater. Herein, we have developed a sulfite-enhanced 11 visible-light-driven photodegradation process using BiOBr/methyl orange (MO) as the model 12 photocatalyst/pollutant system. We found that the degradation rate of MO was greatly enhanced 13 by sulfite, and the enhancement increased with the concentration of sulfite. The degradation rate 14 constant was improved by twenty-nine times in the presence of 20 mM sulfite. Studies using hole 15 scavengers suggest that sulfite radicals generated by the reactions of sulfite (sulfite anions or 16 bisulfite anions) with holes or hydroxyl radicals are the active species for MO photodegradation 17 using BiOBr under visible light. In addition to the BiOBr/MO system, the sulfite-assisted 18 photocatalysis approach has been successfully demonstrated in BiOBr/rhodamine B (RhB), 19 BiOBr/phenol, BiOI/MO, and Bi2O3/MO systems under visible light irradiation, as well as in 20 TiO2/MO system under simulated sunlight irradiation. The developed method implies the 21 potential of introducing external active species to improve photodegradation of organic 22 Page 1 of 25 ACS Paragon Plus Environment Environmental Science & Technology